Author: Andrew Wagner
Date: 15:25:59 04/19/04
Go up one level in this thread
Perhaps some pseudo code will help:
Search(int LeafDistance, int alpha, int beta)
.
.
.
int HashFlag = HashFlagAlpha; //a constant
if (ProbeHash(LeafDistance, alpha, beta, &hashscore, &hash_move))
{
return(hashscore);
}
.
.
.
Gen_Moves();
for (i = 0; i < NumMoves; i++)
{
Make_Move(move(i));
val = -Search(LeafDistance -1, -beta, -alpha);
takeback();
if (val >= beta)
{
RecordHash(LeafDistance, beta, HashFlagBeta, move(i));
return(beta);
}
if (val > alpha)
{
//Add move to PV
alpha = val;
}
}
RecordHash(LeafDistance, alpha, hashflag, Nothing);
return(alpha);
So, Dr. Hyatt, what you're calling a LOWER flag is (I think) what I'm calling
HashFlagBeta, and what you're calling UPPER, I call HashFlagAlpha, becuase those
were the bounds that were exceeded. Personally, I hate this terminology...I wish
we'd use more friendly terminology like AtLeastThisScore or LessThanThisScore. I
think when I rewrite Trueno I'm going to do that, now that I understand
alphabeta a little better. But that's neither here nor there...how does this
look? Andrew
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